Police in Northern Ireland are hunting a violent prisoner who is unlawfully at large after failing to return to prison from temporary release.

William James Patterson, who is 37-years-old, is serving a sentence for four counts of grievous bodily harm with intent, grievous bodily harm, six counts of theft, criminal damage and two counts of robbery.

He was temporarily released from Magilligan Prison on March 18 and was due to return on March 20.

Patterson has so far failed to return.

He is described as being around 176cm tall, of slim build with brown hair and a fresh complexion. It is believed he has connections to Belfast and Dundonald.

Despite exhaustive attempts to arrest Patterson, police have been unable to locate him.

A PSNI spokesman said: "We are appealing to anyone who has seen William Patterson, or who knows of his whereabouts not to approach him but to contact Police on 101 quoting reference number RM20022657.

"Police would also appeal directly to him directly to hand himself in.

"Alternatively, information can also be provided to the independent charity Crimestoppers on 0800 555 111 which is 100% anonymous."